Effect of Surface Area

Question 1

why does increasing the surface area of solids increase the rate?

Answer 1

• more of the solid is exposed to the other particles
• so the collision frequency is higher
• so there are more successful collisions per unit time

Question 2

how is increasing surface area of a solid accomplished?

Answer 2

by cutting up or grinding the solid

Question 3

what is the marble chip experiment?

Answer 3

• the effect of surface area on rate is usually demonstrated by reacting calcium carbonate (marble) chips with hydrochloric acid

CaCO3(s) + 2HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g)

Question 4

what are the variables of the marble chip experiment?

Answer 4

input = the sizes of the CaCo3(s) chips
output = the volume of CO2(g)
control:
- mass of CaCO3(s)
- volume and concentration of HCl(aq)
- temperature

Question 5

how is the volume of CO2(g) measured in the marble chip experiment?

Answer 5

using a gas syringe or inverted measuring cylinder in water

Question 6

what are the results of the effect of surface area on a graph?

Answer 6

comparing the higher surface area line to the original surface area line:

• steeper start = this is because the rate has increase, so the volume of CO2 is increasing faster
• same final volume = this is because the total amounts of reactants hasn’t changed, so eventually the reaction produces the same amount of CO2